A conventional bicycle chain 90 is shown in FIG. 12 and generally includes a plurality of inner plates 94 and outer plates 93, each of the inner plates 94 has two first holes and each of the outer plates 93 has two second holes. Two connectors 92 are connected between two parallel inner plates 94 and two respective ends of each connector 92 are engaged with the first holes of the two parallel inner plates 94. Two outer plates 93 are located outside of two sets of the inner plates 94 and two ends of the two outer plates 93 are connected to two adjacent ends of the two sets of the inner plates 94 by extending two rivets 92 through the two connectors 92 at the two adjacent ends of the two sets of the inner plates 94. Two ends of each pin 91 are engaged with two respective second holes of the two parallel outer plates 93. By this way, the inner plates 94 and the outer plates 93 are continuously connected to form a loop of the chain 90 as shown in FIG. 13.
However, the conventional chain 90 is stiff and lacks flexibility so that when the chain 90 is shifted from one gear to another, a noise is generated and might not be precisely shifted to desired position. This is because there is no gap defined between the rivets 91 and the connectors 92. On the contrary, if the rivets 91 are made to be smaller than the size of the central hole of the connectors 92, the structural strength will not be strong enough to bear the severe operation of the chain 90.
The present invention intends to provide a chain that has better flexibility while the structural strength is maintained.